Higher than normal Idle

[CRDracing]

As the title says I can't get engine to idle normally. (800-1000 Rpms).Ford 2300 with a stock bottom end, stock head, camshaft is .487" lift, 236* duration at .050" lsa 112*. Head has been milled .030". I have installed new engine mounts, lifters, oil pump, replaced rod bearings,cam bearings, aux bearings, and crank bearings. Crank bearings(.003" clearance) and rods bearings (.0025")Ever since these changes I have this high idle problem. I checked for intake leaks and found none. I checked and rechecked timing and lobe center line, and fuel psi (7psi) all okay.It sounds like I have a tight valve but I have between .035" and .044" between the hydraulic lash adjuster and camshaft base circle. Any ideas would be helpful.-Chris

[TM 44]

As the title says I can't get engine to idle normally. (800-1000 Rpms).Ford 2300 with a stock bottom end, stock head, camshaft is .487" lift, 236* duration at .050" lsa 112*. Head has been milled .030". I have installed new engine mounts, lifters, oil pump, replaced rod bearings,cam bearings, aux bearings, and crank bearings. Crank bearings(.003" clearance) and rods bearings (.0025")Ever since these changes I have this high idle problem. I checked for intake leaks and found none. I checked and rechecked timing and lobe center line, and fuel psi (7psi) all okay.It sounds like I have a tight valve but I have between .035" and .044" between the hydraulic lash adjuster and camshaft base circle. Any ideas would be helpful.-Chris

Too low of an idle speed. needs to be at least 1500. 800-1000 way too low for that type cam.

[let-r-eat]

Have you done a compression check on all cylinders and what are the results?

[7uptruckracer]

1300-1500 rpm is the norm on a race motor with any kind of racing cam

[CRDracing]

let-r-eat- the compression cold was 150-140psi 7up and TM- I forgot to mention I can't get the idle below 2700rpm without it stalling.

[Milford Motorsports]

Pull the valve cover,get the crank to TDC on #1. Put an flat piece of metal on the intake and exaust cam lobes,(lobes pointing up).Now measure on both sides of the plate down to the top of the head,both measurements should be the same.If they are then the cam is timed correctly,if not then reset and try again.Set distributor timing at 36* to start,you can always adjust it later.Motor should start,and run with these settings.Also make sure your timing pointer is at TDC while you have motor at TDC.Different pulleys have timing marks in various places.Check the wiring on the distributor,check the carb for broken gaskets,loose parts.

[CRDracing]

Millford- I will try these suggestions tomorrow. Thank you everyone for posting your thoughts, I will let you know tomorrow. -Chris

[let-r-eat]

OK. How far is your idle screw turned? What carburetor are you using? If your engine needs more idle air you may have to drill the throttle plates. The idle screw being screwed in too far exposing the transfer slot will mess things up big.

[7uptruckracer]

I agree If your idle screw is too high and you have to much of the transfer slot covered you need to either drill a hole in each idle plate (after checking for leaks) assuming all your timing and ignition stuff is right. I'd go 1/8" hole or 3/16"

[84Dave]

Mr. Milford....... Correct me if I'm wrong, but I believe your method of checking cam position(E-bar) is only valid if both the intake & exhaust lobe heights are the same? CRD....... If you're running a Holley 350 or 500 2-bbl on the engine, with their transition slots. Look at the carb 'slots & butterfly position from the bottom side. The idle screw should be adjusted until a small square of the idle/transition, about .020"x.020", shows visually under the closed throttle blades. That slot position will keep the engine from going 'pig rich' at idle with the position screw, AND when you get out of the throttle going into a corner with a relatively high vacuum in the intake manifold. I've always used one of two options to correct the idle speed with the above physical settings. Drill holes in the throttle blades, as has been suggested. OR.......If the carb has a big vacuum fitting in the base-plate, I've had good success with a 'drilled pill', allen set-screw, inside a thick hose attached to the vacuum fitting. The size of the drilled hole increases the idle-air introduced at the base of the carb and allows the idle set-screw to remain in a position for best fuel from the transition slot. -Dave-

[CRDracing]

Okay I have tried most all suggestions (except drilling/ creating a metered air leak in the carb) mostly because I didn't have this higher idle problem prior to installing these new parts. I took the lifters out of the cyl. head and inspected the height and inspected the cam follower. The follower looks as if it is digging into the valve stem. Also the stem seems to have lost some of the chamfer at the top. The lifter has the same overall height but is vastly different in measurements when broken up into the body and plunger. IE the new plunger is longer but the new body is shorter thus its the same overall length. The major difference on the lifter I see is the base of the new lifter is chamfered about 1/16" and the old lifter is stepped(has no chamfer.) Since I don't have an overall height issue I am thinking I shimmed the oil pump(melling m127) pressure spring too much causing the increased pressure on the hydraulic lash adjusters which could be turning them into a solid lash adjuster. I have pictures but don't know of a way to get them on here because I'm unfamiliar with the process. Does my logic seem off...? Any thoughts? Thanks for all your help thus far!-Chris

[CRDracing]

And I can't throw the old lifters back in due to the metal that went through the engine.....

[CRDracing]

Hey guys just giving an update. After many phone calls and head scratching, Brian from Esslinger took a snap shot of his carb metering block to reaffirm me that it was suppose to have 4 plugs at the top. When I got home there was only two plugs installed in my "NEW" holley carb metering block. It appears they have fallen out. Installed new metering block and it purrs like it use to. Thanks for everyone's help! -Chris

[7uptruckracer]

Good Job! Those are tough to find holly actually redesigned their metering blocks a few years back that they send out with the new carbs its the HP style without the adjustiablilty so it doesn't even look like the old one so it makes finding out and comparing even harder glad you found it!

[CRDracing]

Thanks for all you help! It idles at 900-1100 rpm now and the fuel is no longer pouring out the boosters! It still has an idle problem(sounds like it drops a cyl.) once it comes off high rpm(5k). Then it will slowly start to smooth out and idle like it should. We are trying an oil restrictor for that problem. I will report back as soon as we install it. -Chris

[7uptruckracer]

I had a problem with low speed idle circuit and to little base timing being i didn't run mine fully locked out all the time if you don't lock yours out make sure you have at least 18* base timing